The present disclosure relates to an information processing device, an information recording medium, an information processing method, and a program, and more particularly, to an information processing device, an information recording medium, an information processing method, and a program performing, for example, data recording involving format conversion.
As information recording media recording various kinds of content such as movies and music, DVDs (Digital Versatile Discs) or BDs (Blu-ray (registered trademark) Discs) have been considerably used.
In information recording media such as discs, images, audios, and various kinds of data such as reproduction control data are recorded with predefined data recording formats.
For example, the BDMY (Blu-ray (registered trademark) Disc Movie) format is used as a data recording format for BDs.
In order to reproduce recorded data with the BDMV format, it is necessary to retain a program for reproduction of BDMV format data.
The BDMV format data includes a clip AV stream file in which reproduction target data is recorded, a playlist file serving as a reproduction control information file, a clip information file.
Image or audio data which is the reproduction target data is stored in the clip AV stream file, but the clip AV stream file is recorded according to the MPEG-2 TS format including TS (Transport Stream) packets.
The copyrights, the distribution rights, or the like of many pieces of content such as music data and image data recorded in information recording media such as BDs are owned by generators or sellers. Accordingly, when the content is stored in such information recording media and supplied to users, use control is generally performed to permit only users who have regular use rights to use the content.
Specifically, for example, content is recorded as encrypted content and control is performed to allow the content to be decrypted with only encryption keys supplied to users legitimately purchasing the content. However, when such a process is performed but, for example, users acquiring the encrypted content illegally distribute or publicize the decrypted content or the encryption keys, unspecified peoples may illegally use the content. In particular, illegal publicization or delivery of data via networks occurs in many cases in recent years, and thus how to prevent such illegality is a big challenge.
As the encrypted structure of data corresponding to the BD described above, there is a structure in which a device performing a decryption process based on decrypted (plain text) content can be determined.
This structure is a structure in which a device analyzing decrypted content generated by decrypting encrypted content, e.g., decrypted image data, and performing a decrypting process based on identification data extracted from an image is determined.
For example, Japanese Unexamined Patent Application Publication No. 2007-43336 discloses a structure in which source tracking can be performed.
In the structure disclosed in Japanese Unexamined Patent Application Publication No. 2007-43336, a plurality of pieces of variation data are set in a segment which is content structure data, e.g., image data of one scene including movie content. The plurality of pieces of variation data set in a segment region are data which can each be decrypted with different keys.
Each reproduction device selects, decrypts, and reproduces one piece of decryptable data from the plurality of pieces of variation data by applying a key (segment key) which can be used by the reproduction device and corresponds to a reproduction device.
That is, the different variation data is selected and reproduced according to the reproduction device and reproduction is performed along a different reproduction path according to the reproduction device.
For example, when copy data of decrypted content is circulated via a network, a device having decrypted content can be specified in a certain range by analyzing the variation data or the reproduction path included in the content.
Further, an encryption key (decryption key) stored in each reproduction device is different according to a maker or the like of the device, and thus a source can be tracked according to such a set unit.
On the other hand, in recent years, users who watch content such as movies with portable terminals such as smartphones or tablet terminals have increased.
Such portable terminals may not mount reproduction applications corresponding to the foregoing MPEG-2 TS format or the BDMV format.
Accordingly, when recorded data of BDs are copied to media of portable terminals, it is necessary to convert formats into formats which are not the BDMV format and with which the reproduction applications of the portable terminals can reproduce the recorded data and record the content.
A process of copying data between media is described in, for example, Japanese Unexamined Patent Application Publication No. 2008-98765 and Japanese Unexamined Patent Application Publication No. 2011-222078.
As a data recording format standardized in consideration of use by portable terminals, there is the MP4 format (hereinafter referred to as the MP4).
Many portable terminals have reproduction applications which can reproduce MP4 data recorded with the MP4 format. When content is recorded in media of the portable terminals, the content is necessary to be recorded with the MP4 format.
However, encryption modes permitted in the MPEG-2 TS format and the MP4 format, e.g., encryption algorithms or applicable key data structures, may not accord with each other. Accordingly, for example, when MPEG-2 TS format data including the variation data for which the above-described source tracking can be performed is converted into data with the MP4 format to be recorded, it is necessary to perform a process of decrypting the variation data recorded according to the MPEG-2 TS format once and re-encrypting the data to form data with an encrypted structure according to the MP4 format.
However, variation data which can decrypt a reproduction device is only one piece of variation data in the plurality of pieces of variation data set in one segment region.
Accordingly, a process of decrypting all of the pieces of variation data and re-encrypting the data may not be performed.